I dont know, i dont have problems with Ezio at Crucible. Yes, he is hard to hit him, but its still possible to fight. You may crash him with ultimates at start, use Arachna to stop him with her web. I use Selena's beam when Ezio is vulnerable. At my experience, he is not annoying at all - Kong, Lumos, Xanos caused a lot more troubles.
I guess it just relates to one's strategy for sweeping up CoF levels. For me, Ezio is the only frontline foe that escapes devastation from Kong's LingLing-powered ultimate. Kong is only a pain if you somehow have no ultimates charged when facing him, Xanos is a heavy damage dealer but is squished much easier than Ezio because he doesn't avoid attacks... but Lumos? How does he cause a lot of trouble?
For me, it is only Ezio that can escape the initial slaughter due to his auto-dodge, and if he gets away for too long he ultimates like 12312 times during the battle (at least the awakened ones do), while my team acts like they all took sleeping pills and strong opioids before the fight.
If only he didn't auto-dodge while sleeping...